[sdiy] Vangelis & keyboard key vibrato/tremolo/modulation

[anthony]

I was watching a video of Vangelis playing  a keyboard and I couldn't tell 
which oneit was. It looked like he could get vibrato from waggling his 
finger on the key much like a cellist might do the same on the fingerboard. 
Was I seeing what I tawt I taw? What keyboards do this? Or is he just really 
good at getting responces from velocity and aftertouch?

AA